The invention relates generally to ultrasound systems and more specifically to a system and method to control an adaptive beamformer system used in the ultrasound system.
Ultrasound systems comprise an array of transducer elements used for transmitting ultrasound energy into an imaging subject. The transducer array transmits ultrasound energy and receives backscattered ultrasound signals from the imaging subject to create and display an image. The backscattered signals are processed to create and display an image.
Typically, an ultrasound system comprises a transmit beamformer to transmit a beam of ultrasound energy. The ultrasound system further comprises a control processor that sends command data to beamformer system to create a beam of a desired shape. Similarly, a receive beamformer system performs time delaying and focusing operations according to the instructions from the control processor to create received beam signals. The received beam signals are then processed to generate the ultrasound image.
The ultrasonic imaging system described above assumes that there is a known, constant speed of sound in the medium through which the ultrasonic pulses are conveyed. If the sound speed is not constant, sound pulses transmitted from certain elements in the array can arrive earlier or later than expected at the desired focal point and will not properly combine with the other pulses. As a result, the net transmitted wave will not be optimally focused. Similarly, on reception, the signals on each element in the array will not be delayed optimally before summing so that the receive focusing will be degraded. If the deviations from the assumed propagation times could be measured or estimated, the ultrasound image could be improved by correcting the applied time delays for the deviations. Such an imaging system is said to contain an “adaptive” beamformer system to distinguish it from a beamformer system in which the time delays are fixed and predetermined.
One way to correct the erroneous received beam signals is by measuring the arrival time errors measured for an acoustic line in one frame and applying the measured error on the same acoustic line in the next frame. Such a method may not be entirely accurate when the transducer is moving rapidly, since in general the arrival time errors will vary with the position of the transducer with respect to the imaging subject. In addition, any adaptive beamformer system may produce image artifacts or degrade the image in other ways in some circumstances.
It is therefore desirable to design an adaptive beamformer system for use in an ultrasound system where the adaptive beamformer system may be disabled or enabled accordingly. It is further desirable to indicate to a user using the ultrasound system the state of the beamformer system and also to allow the operator to reset the beamformer system to default time delays when desirable